1. Field of the Invention
The present invention relates generally to an actively controlled suspension system for an automotive vehicle. More specifically, the invention relates to a suspension control system which has adjustable of suspension characteristics in the suppression vehicular pitching.
2. Description of the Background Art
The U.S. Pat. No. 4,702,490, issued on Oct. 27, 1987, to Hirotsugu YAMAGUCHI et al., and assigned to the common assignee of the present invention, discloses an actively or positively controlled automotive suspension system which includes a hydraulic cylinder for generating variable damping force against relative motion of a vehicular suspension member and a vehicle body in bounding and rebounding directions for adjusting suspension characteristics and adjusting vehicle body attitude.
A similar type actively controlled suspension systems has been disclosed in the co-pending U.S. patent application Ser. No. 060,911, filed on June 12, 1987 and assigned to the common assignee to the present invention. Further, European Patent First Publications 02 49 209, 02 49 227 and 02 49 246 respectively corresponding to co-pending U.S. patent application U.S. patent applications Ser. Nos. No. 059, 888 (filed on June 9, 1987), 060,856 (filed on June 12, 1987) and 061,368 (filed on June 9, 1987), both of which have been assigned to the common assignee to the present invention. The above-mentioned three inventions include features of pitching-suppressive suspension control for adjusting damping characteristics at respective vehicular wheel for suppressing vehicular rolling motion.
The aforementioned prior proposed suspension control systems are effective in suspension control for adjusting or regulating vehicular attitude. Such prior proposed suspension control systems are effective for suppressing pitching motion in response to change of load at various position on the vehicle. On the other hand, when the pitching motion is caused depending upon the suspension geometry of the vehicle, it is not satisfactory in suppressing pitching motion.